Home Valve ComparisonsWafer vs Lug Butterfly Valve - Which Mounting Style Do You Need?

Valve Comparison Guide

Wafer vs Lug Butterfly Valve - Which Mounting Style Do You Need?

Wafer vs lug butterfly valve: end-of-line service, flange compatibility, installation differences and API 609 requirements explained. Choose the right butterfly valve mounting style.

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Use a wafer butterfly valve for all in-line (not end-of-line) service where the valve is permanently sandwiched between two flanges and the downstream pipe remains connected. Use a lug butterfly valve when the valve is at the end of a line, at a pump discharge/suction connection, or anywhere the downstream pipe section may need to be disconnected for maintenance without disturbing the valve or upstream piping..

Overview

Wafer Butterfly Valve

A wafer butterfly valve is sandwiched between two flanges using long bolts that pass through both flanges and clamp the valve body. Wafer valves have a very compact face-to-face dimension and are the least expensive butterfly valve mounting style.

DN50–DN1200, Class 150, elastomeric or PTFE lined, API 609 Category A

Lug Butterfly Valve

A lug butterfly valve has threaded lugs (ears) cast or drilled into the valve body. These lugs accept bolts from each flange independently - the two flanges do not share the same bolts. This allows the downstream flange and pipe to be removed independently without disturbing the upstream flange.

DN50–DN600, Class 150–300, ductile iron / CS / SS, API 609 Category A

Wafer Butterfly Valve or Lug Butterfly Valve?

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Relevant Products

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Pros & Cons

Wafer Butterfly Valve

Lowest cost - lightest and simplest construction

Very short face-to-face - saves space and weight

Available up to DN1200 in standard range

Easy installation - slides between flanges

Wide range of materials and liner types available

Cannot be used in end-of-line (dead-end) service - no flange on the downstream side means valve body is unsupported

Removing the valve requires unbolting both flanges (full pipe separation)

Flange bolt holes must be compatible with the valve - limited to specific flange standards

Cannot handle full pipeline pressure on one side with nothing on the other

Lug Butterfly Valve

End-of-line (dead-end) service - downstream flange can be removed

Each flange connects independently - one side can be removed without disturbing the other

Better for systems that require periodic disconnection of downstream pipe sections

Full flange pressure rating even without downstream pipe connected

More versatile installation - works in any pipeline configuration

More expensive than wafer type - machined lugs add cost

Heavier than wafer butterfly valve

Slightly longer face-to-face than wafer type

Lug threads must be maintained - corrosion can cause stud seizure

Wafer Butterfly Valve vs Lug Butterfly Valve - Specification Comparison

Parameter	Wafer Butterfly Valve	Lug Butterfly Valve
Body Style	No lugs - bolts pass through both flanges	Threaded lugs - each flange bolts independently
End-of-Line Service	Not suitable - no downstream support	Yes - downstream pipe can be removed
Disassembly	Must separate both flanges to remove valve	Can remove one flange without touching the other
Cost	Lower	Higher (machined lugs)
Weight	Lighter	Heavier
Face-to-Face	Shorter	Slightly longer
Flange Standard	Must match specific flange bolt hole pattern	More flexible - each side independent
API 609 Category	Category A	Category A (lug) / Category B (flanged)
Pressure Rating	Class 150 standard	Class 150–300 (lug); Class 600 (triple-offset)

When to Use Each

Use Wafer Butterfly Valve when:

General purpose pipeline service (water, HVAC, cooling water)

Large bore applications where end-of-line service is not needed

Fire suppression systems where full pipeline is always pressurised

Where weight, cost and space saving are priorities

HVAC ductwork and building services

Use Lug Butterfly Valve when:

End-of-line service - pump and equipment isolation from downstream

Systems requiring frequent downstream disconnection

Large bore isolation valves where downstream pipe may be removed for maintenance

Locations where full flange pressure rating is required on both sides

Water and wastewater treatment plant valves at pump suction/discharge

Decision Guide

Frequently Asked Questions

What does end-of-line service mean for a butterfly valve?

End-of-line (or dead-end) service means the valve is at the terminus of a pipeline - there is no downstream pipe or flange when the valve is in service. A wafer butterfly valve cannot handle this because the body depends on both flanges to support it. If the downstream flange is removed, the valve body can blow out under pressure. Lug butterfly valves are designed for this service - each lug accepts its own bolts independently, so the upstream side can hold full pressure even when the downstream side is open.

Can a wafer butterfly valve be converted to lug type?

No - wafer and lug bodies are different castings. You must specify the correct mounting style at time of order. If you need end-of-line service and already have wafer valves installed, you can install a blind flange on the downstream side of the valve to convert it to a supported installation - but this is a workaround, not a true lug-type installation.

Reviewed by Application Engineering, Vajra Industrial SolutionsDiscipline: Valve Application EngineeringLast reviewed: 20 June 2026